Description of Asthma

The lung is the main organ of the respiratory system and its main function is respiration (exchange of gases between the environment and the body). Air enters the nose where it is filtered, warmed and humidified. After passing through the trachea (windpipe), the air travels into the lungs through the bronchi (a system of branching airway tubes that become smaller as they reach deeper into the lung). The smallest of the bronchi, the bronchioles, open into balloon-like sacs called alveoli.